“The 6.5x54
Mannlicher-Schönauer is a 6.5mm (.264" cal.) rifle cartridge used in
the Mannlicher rifle. 6.5mm bullets are typically known
for their high ballistic coefficients and sectional density, which
gives them great stability in flight, resistance to wind deflection,
and excellent penetration.

Among professional elephant hunters of the 19th and 20th centuries,
Walter Dalrymple Maitland "Karamojo" Bell, who shot more than 1,000
elephants in the period 1895-1930, had a very high regard for the
6.5mm Mannlicher-Schoenauer, and had Daniel Fraser of Edinburgh,
Scotland build him a special, lightweight rifle in that calibre. He
only set it aside when he was unable to acquire dependable
ammunition for it, and turned to a .275 Rigby Mauser magazine rifle
instead. The .275 Rigby cartridge is interchangeable with the 7 x 57
mm Mauser. Bell's legendary name has remained closely linked with
the 7mm Mauser, but the 6.5 Mann.-Sch. was his first preference.

A modern cartridge, the 6.5mm Grendel very closely duplicates the
ballistics of the 6.5 mm. The American cartridge, the .257 Roberts
also demonstrates many of the virtues of the 6.5 x 54mm. The .257
Roberts was originally designed as a wildcat cartridge by Ned
Roberts, and is based on the 7 x 57mm cartridge. Note that the 6.5 x
54mm shoots a .264" bullet.

The 6.5 x 54mm was referred to by the writer Ernest Hemingway as the
.256 Mannlicher. Though it never replaced his favorite 30-06
Springfield, he did speak highly of it as a lion cartridge, and it
was the favorite of his African guide and professional hunter
Phillip Percival. The Kenya game warden and naturalist A. Blaney
Percival also favored the 6.5 x 54mm.

In part, the 6.5 x 54mm's reputation stems from its use of a
160-grain (10 g) bullet, giving the projectile very high sectional
density and therefore penetrating ability. It requires a fast
rate-of-twist rifling (about 1 in 9") to stabilize such a long
bullet."